Preparation of halophosphate phosphor to obtain a deagglomerated powder is known. U.S. Pat. Nos. 3,654,173 and 3,654,174 to Thomas et al disclose a method of making such a phosphor whereby during synthesis the phosphor particles are maintained in continuous motion or agitation to prevent substantially any agglomeration thereof.
U.S. Pat. application No. B 345,390 to Demarest et al discloses a method of making such a phosphor whereby deagglomeration of the phosphor crystals occurs by high-shear mechanical stirring of the phosphor in an aqueous slurry.
U.S. Pat. No. 3,023,339 to Vodoklys discloses a method of making such a phosphor whereby an aqueous slurry containing the phosphor is fed into a spray dryer, where it is atomized in a hot gas or air stream and exposed to temperatures well above the boiling point of water to rapidly evaporate the water, leaving a fluffy, deagglomerated phosphor powder. The gas or air stream is heated indirectly to about 600.degree. F. (316.degree. C.). The dried phosphor and evaporated water are fed into a conventional centrifugal separator, or cyclone collector. The air stream is forced into a circular path and deposits a substantial portion of the phosphor powder via centrifugal forces in the bottom of the cyclone collector. Residual phosphor dust remaining in the circulating stream is collected in a dust collecting bag, while the circulating stream is vented to the atmosphere. Recovery efficiency of the process is about 95 percent.